package 数据结构.映射.链表映射;

import 数据结构.映射.Map;

/**
 * @author Veng Su 1344114844@qq.com
 * @date 2018/7/24 9:41
 */
public class LinkedListMap<K,V> implements Map<K,V> {
    private class Node {
        public K  key ;
        public V value;
        public Node next;

        public Node(K key,V value, Node next) {
            this.key=key;
            this.value=value;
            this.next = next;
        }

        public Node(K key) {
            this(key,null, null);
        }
        public Node(){
            this(null,null,null);
        }

        @Override
        public String toString() {
            return "Node{" +
                    "key=" + key +
                    ", value=" + value +
                    '}';
        }
    }

    private Node dummyHead;
    private int size;

    public LinkedListMap() {
        this.dummyHead=new Node();
        size=0;
    }
    public Node getNode(K key){
        Node cur=dummyHead.next;
        while (cur!=null){
            if (cur.key.equals(key)){
                return cur;
            }
            cur=cur.next;
        }
        return null;
    }

    @Override
    public void add(K key, V value) {
        Node node=getNode(key);
        if (node==null){
            dummyHead.next=new Node(key,value,dummyHead.next);
            size++;
        }else {
            node.value=value;
        }
    }

    @Override
    public V remove(K key) {
        Node prev=dummyHead;
        while (prev.next!=null){
            if (prev.next.key.equals(key))
                break;
            prev=prev.next;
        }
        if (prev.next!=null){
            Node delNode=prev.next;
            prev.next=delNode.next;
            delNode.next=null;
            return delNode.value;
        }
        return null;
    }

    @Override
    public boolean contains(K key) {
        return getNode(key)!=null;
    }

    @Override
    public V get(K key) {
        Node node=getNode(key);
        return node==null?null:node.value ;
    }

    @Override
    public void set(K key, V newValue) {
        Node node=getNode(key);
        if (node==null){
            throw new IllegalArgumentException("key 不存在");
        }else {
            node.value=newValue;
        }
    }

    @Override
    public int getSize() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size==0;
    }
}
